1. The lesson hasn't started yet.
2. The teacher has already written on the board.
3. Joe and Lm (???) have just come into the classroom.
4. Tony hasn't finished getting his books ready.
5. Christine has already opened her book.
6. Dave has dropped his pen on the floor.
7. He hasn't picked it up yet.

câu 7 khum chắc em nhé, vì cụm "it u p" hơi khó hiểu 
nhưng chúc em học tốt nhaa^^

1.The lesson  has not started yet

2.The teacher has already written on the board

3 Joe and Lm have just come into the classroom

4 Tony has not finished getting books ready

5 Christine has already opened book

6 Dave has dropped  the pen  on the floor

7 He has not picked  it up yet

+

+

`\text{S + has / have + V_pII}`

`\text{S + has/have + not + V_pII`

`\text{Has/have + S + V_pII`